Derren Brown, a British illusionist famous for his mind-reading act, set out to prove just how susceptible we are to the many thousands of signals we're exposed to each day. He approached two creatives from the advertising agency Saatchi & Saatchi for the "test." On their journey to his office, Brown arranged for carefully placed clues to appear surreptitiously on posters and balloons, in shop windows, and on t-shirts worn by passing pedestrians.
Very interesting article as to how Whole Foods subtly markets to you from the minute you enter the store. I will keep a sharp eye out for these tricks in the future!